In our discussions about U. S. History, I may use reference groups of people in different ways as a means to contextualize a time period. For instance, Negro suffrage may be used in reference to the fourteenth amendment.
To address the concern about the use of "Indian": This term is both a historic reference and it be a politically correct term, though the proper term is "American Indian." I have tried to gather a little evidence. Here are a couple of links, albeit one is from wikipedia.